Stemming wad for blastholes



Feb. 15, 1944. B A OLSEN STEMMING WAD FOR BLAST HOLES Filed March 5, 1940 ma ln'ToRNEY Patented F eb. 15, 1944 UNITED? srAres vNr orifice 2,341,944 STEMMING WAn FOR BLAs'rHoLEs Application March 5, 1940, Serial No. 322,315

3 Claims.

This invention relates to prepared wads of resilient material used as tampons for closing recesses or apertures.

It is an object of the invention to provide a stemming Wad which is i'lreproof. f

Another object of the invention is to provide a stemming wad which is not buoyant and therefore will not be carried in sump water into the intake ducts of pumps where it might foul the intake valves of the pump and incapacitate the latter.

The invention possesses other objects and feae tures of advantage which will be brought out in the detailed description of the invention hereunto annexed. It is to /be understood that the invention is not to be limited to the specic form thereof shown and described as variants thereof may be employed within the scope of the appended claims.

Referring to the drawing:

The gure is a View, partly in side elevation and partly in vertical section, showing the stemming Wad of my invention.

In the drawing I have shown the preferred form of my invention. In this case I pre-form a wad of cotton or other bers 9 and then either dip the wad into a liquid bath which will deposit a surface coating il on the wad or, preferably, I spray the liquid on to the wad so as to form the coating. The coating material is composed of a liquid vehicle, which in itself is capable of rendering the iibrous material reproof or highly resistant to combustion, such as fluid solutions of alum, borax, sodium silicate, sodium tungstate or zinc chloride. liquid vehicle is composed of a material which is both lreproof and insoluble in water such as a duid phenol or aldehyde resin the nature of liquid Bakelite In this fluid vehicle is mixed, preferably, metallic powder such as aluminum, Jronze, etc. Sufficient of the liquid is sprayed in to the surface of the bers 9, or deposited on Lhe surface by dipping the wad in a batch of the uid material, to provide a coating in which sufcient metallic material is contained to over- :ome the buoyancy of the cotton and to cause it yo sink when placed in water. Thus, if the wad, titer being used in a blast hole, should happen yo iind its way into water drainage ducts, it will )e too heavy to be carried by the water into the nine pump and there possibly clog the intake or exhaust valves so that the pump will be rendered noperative. It will be seen that the reason for )roviding a Waterproof coating material is to vreclude the possibility, should the wad become Preferably however the immersed in water, of the water dissolving the coating and thereby rendering the wad buoyant so that it may be carried by the water current into the pump.

After the blasting charge has been placed in the hole, and the blasting cap and fuse have been placed, the stemming Wad is inserted in the hole and driven home by the ramrod. After being bottomed, the wad is forcibly tamped by the ramrod. This compresses the cotton causing the mass of the latter to expand radially and force it into any pits or irregularities in the bore hole so that the wad is thus securely locked in the hole. It will be seen that the fuse may burn past the wad without setting the latter are since the coating and the metal particles embedded therein shield the cotton from being ignited. The coating also protects the cotton against ignition by the flash of the blast.

During cleaning up of debris after the blast, should the stemming wad happen to nd its Way into the ditches carrying off seepage water, it will not be borne by the water into the pump sumps since the heavy metal in the coating will preclude this by rendering the wad incapable of iioating in the water.

Due to the fact that it is reproof, the stemming wad of my invention 'may be safely used in coal mines or, in other operations where inflammable dust is present, since it may not be ignited by either the burning fuse or the ash of the blast and thereby possibly cause ignition of the dust. Also, due to the presence of the relatively stiff coating covering thebrous material, the stemming wad may be more tightly packed in the blast hole than may a resilient wad of untreated bers thus causing the wad to more tenaciously grip the sides of the bore. Furthermore, the fibrous wad provides a shock absorber between the end of the ramrod and the firing cap which greatly lessens the danger of premature blasts due to accidental discharge of the cap by shock. r

Having thus described my invention in detail, what I claim as new and desire to secure by Letters Patent is:

1. A tamping wad of the class described having a shaped body and a covering therefor, the entire body being formed of brous material and comprising a mass of unimpregnated loosely aggregated bers, the covering completely enveloping the body and adhering to and constituting a binder for the bers at the exterior of said lbody, said covering being reproof, insoluble in Water and including a sunicient quantity of comminuted 2 n metal to overcome the natural buoyancy of the body of fibrous material and thereby to cause the body to sink when placed in water.

2. A tamping Wad of the class described having a shaped body provided with a skin coating, said body fbeing formed entirely of fibrous material and comprising a mass of unimpregnated loosely aggregated fibers, the skin coating completely enveloping the body and adhering to and constituting a binder for the fibers at the exterior of said body, said skin coating being insoluble in Water and including a suidcient quantity of comminuted metal to overcome the natural buoyancy of the body of fibrous material and thereby to cause the body to sink When placed in Water.

3. A tamping Wad of th'e class described having a shaped body provided with a skin coating, said body being formed entirely of iibrous material and comprising a mass of unimpregnated loosely aggregated bers, the skin coating completely enveloping the body and adhering to and constituting a binder for the fibers at the exterior of said body, said skin coating being formed of reproof material and including a sufficient quantity of comminuted metal to overcome the natural buoyancy of the 'body of brous material and thereby to cause the body to sink when placed in water.

BURTON A. OLSEN. 

